1. Field of the Invention
The present invention relates generally to container security and supply chain management and, more particularly, to the internal communications within a shipping container security system which needs to provide a high degree of operational reliability.
2. Background of the Invention
In today's security conscious transportation environment, there is a strong need to cost-effectively and accurately monitor the contents of containerized shipments. This need exist both in the United States and abroad.
Despite the strong need, no present solution has been able to provide the protection and accuracy needed to suit the transportation industry and the government agencies charged with monitoring shipments. This lack of an acceptable solution is due to many factors which complicate interstate and international shipping. Shipping containers are used to transport most of the commerce entering, leaving, and transiting or moving within the United States. It is estimated that there are over 6 million containers moving in global commerce. Shipping containers have revolutionized the transportation of goods by greatly reducing the number of times goods must be loaded and unloaded during transport. However, at the same time, this same advantage has created a major problem in that it is very difficult to monitor and track the contents of each container during transport.
Beyond their basic construction, monitoring the content of shipping containers is also difficult because these containers are carried through numerous transit points and depots all over the world and it is impractical to stop and check the contents of each container individually at each point of transit. Dealing with this problem, the U.S. Customs Service estimates it can inspect just 5% of the 6 million containers entering and reentering the U.S. each year. Accordingly, agencies such as the United States Customs Service are seeking improved ways to achieve cargo container security and integrity upon arrival at the ports of entry of the United States.
To date, many government agencies have initiated programs to improve container security. These include many useful elements that are intended to preclude their use by terrorists. However, at present, none of the container tracking systems in use provide a way to assure the integrity of the contents of the containers to assure global container security. Current computer tracking systems are effective at monitoring the location of individual containers from point of origin to destination and maintaining an inventory of loaded and empty containers. Most of these systems rely on transponders mounted on the containers that send messages to satellites or ground stations, from which the messages are rerouted to shipping companies, freight forwarders, and companies. However, these tracking systems are unable to guarantee that a given container does not contain contraband. Furthermore, the proper operation of the communication devices of these systems is critical, and when it is not possible to communicate, the entire functionality of the system is compromised. The invention described herein, provides a safe and reliable alternative method of communication when the primary communication means are not available.
3. Description of the Related Art
A container security system as described by System Planning Corporation (SPC) (U.S. Pat. No. 7,098,784) herein referred to as “the SPC Invention”, performs many of the functions to monitor containers, their content, and to detect tampering within a container during transit. This is accomplished through a device is which located on a container, which performs multiple functions. Some of these functions may include controlling various sensors, collected the data from these sensors and transmitting this data back to a central monitoring station. The central monitoring station may also send commands and information to individual containers equipment with this device.
To enable information to be transmitted to and from the container, there are several communications subsystems including a satellite or cellular communications device, or both. This system also describes the utilization of a short range wireless or local area communication channel to communicate with various sensors and other elements within the container. The system utilizes the satellite or cellular communications channel to communicate and send status and alarms to a central monitoring station.
In the SPC invention, the short range wireless channel is generally used to interface with various external sensors such as container door position, proximity sensors, and other sensors which are not physically located in the controller and communications unit but are within the container.
The cellular and satellite channels are used to relay information collected from the sensors, including location, and other information related to the container, back to a central monitoring station located in a different geographical area, in most cases some distance away.
In some cases the satellite or cellular communications channel as described in the above invention by SPC is not capable of providing reliable communications. This is because of poor radio frequency propagation characteristics when containers may be stacked in a yard, stacked on the deck of a ship, or located within the hull of a ship. This may occur for the satellite mode when a container does not have a direct line of sight to an overhead satellite, or a there is some obstruction where the satellite link cannot be closed.
On the cellular side, this may also occur because of weak or poor radio frequency signals, such as is commonly seen within a building, or if a particular container may be within the hull of a ship or out of range of a cellular tower or base station.
To address the problem and limitations noted above, a system which can provide an alternative communications path from any given container to the central monitoring station is provided. In the invention described by Mesh Networks, Inc. (Maitland, Fla.) titled “Ad Hoc peer-to-peer mobile radio access system interfaced to the PSTN and cellular networks” (U.S. Pat. No. 6,961,575), a system is described for the cellular network application which provides the basis for a dynamically configurable network comprised on multiple elements, each of which can communicate with the each other on a peer-to-peer basis.
The limitation of this and other inventions related to ad-hoc networking is that they are specifically directed toward applications in wireless communication networks such as cellular or radio, and that they do not apply these concepts to that of a container security system.